Next month's census will include a question about religious affiliation. How should it be answered? Humanist organisations are hoping that it will reveal that Christianity is crumbling, and that the old argument that "if none, write C of E" will finally be exploded. Christians on the other hand hope that it will show the enduring if unfashionable strength of their conviction. Almost everyone wants to know how many Muslims there are.

So a number of questions arise. The first is whether religious affiliation still matters. Should the government be measuring it? What should happen with the results? It's difficult to imagine a political use for these figures that does not make religious affiliation, or lack of it, something which should be considered when making political choices. "Vote Nick, he's an atheist" is surely no more compatible with secularism that "Vote Dave, he's a Christian", or "Vote Saeeda, she's a Muslim". This may be unavoidable. But is it what we want?